Do you ever release serious errors into prod?
So ideally you have some kind of monitoring that reports/shows how many services are alive (and where they live in a cluster), how many errors they generate etc. Then based on some thresholds you can take them out of circulation and let them cool down. If certain kinds of errors occurs, or at a certain frequency, the system can notify a site reliability engineer (or equivalent) to check it out. Then they can decide if it should be permanently removed and to log an internal support ticket and so forth for the developers or product teams.
Production issues are a part of life. You need to have some visibility on issues and their severity. Every company and tech stack is different, also depending on their SLA's and uptime promises.
Ads not rendering in an app might be less severe than a pump failure at a fuel station, so they have different kinds of monitoring and and reaction times to faults. Obviously things like hospitals, banks, airlines/aircraft manufacturers have way different requirements and infrastructure from say a system that manages all school libraries for a state/province.
There are too many products and approaches to mention here if you were looking for a list of those. I have one or two favorite approaches and a handful of tools for this kind of stuff, half of which is homemade, so not something you can google. But you can google it and see a few different approaches. "microservices monitoring java" or "microservices monitoring best practice" or something along those lines will get you on a path. Try to find 5 different approaches and reflect what each one is missing or how they may help you, and then ponder what would you like to see from a reporting system with hundreds/thousands of services.
And then obviously the the best lessons will come from production itself.
Good luck!
Only if you accept them. The alternative is to do very few, rigorously tested releases per year. This way you don't have production issues. That's how industries like banking make sure bank transfers and card payments work and people's money is not randomly lost... It's a shame many other industries just accept their product failing for users as something normal/inevitable.
We did four releases a year, across the entire organization (so mainframe and more modern platforms), on Saturday nights/early Sunday mornings. There was plenty of testing but there was still plenty of errors only found on the day of, and rushed to fix in the wee hours or daylight hours of Sunday morning.
The only thing that seemed to correlate with release quality was the overall risk of the release, i.e. the complexity and number of new features written during that quarter.
This way, you had bugs in prod for less than a day once every quarter, as opposed to having buggy prod all the time, as is common in organizations doing Continuous Deployment.
Luckily, a good CI/CD pipeline makes reversions just as easy as deployments. So even when you have errors, it's easier to correct than if you suddenly discovered "our deployment bash script / ansible playbook isn't as reversible as we thought it was"
The idea of deploying every commit all the way to prod is is very questionable.